Receiver for rotating lasers used for guiding machines, particularly public works machines

ABSTRACT

Receiver for rotating lasers used for guiding machines (for example public works machines), which comprises a receiver assembly proper (6) disposed on a support (9) enabling it to be fastened on the machine, a cell consisting essentially of plates (7) carrying photodiodes (8) and disposed around a fixed shaft in such a manner as to form a pillar enabling the passage of the beam to be detected over 360°, the assembly being protected by a peripheral shell (28) capped by a protective hood (27). The photodiode (8) plates (7) are three in number and are disposed vertically around a central support shaft to form between them an angle of 60° to one another, the mounting being effected in such a manner that they are detachable and their fastening being achieved with the aid of damping members disposed at each end of the plate support shaft (7) and around the latter.

The present invention relates to a new type of receiver for rotatinglasers used for guiding machines in the field of public works,agriculture or even industry.

In the present description the invention will be described for areceiver used in the public works field, but this is not limitative anda receiver of this kind could also be used in any other field wheresimilar problems arise.

In the field of public works, for leveling ground or adjusting the slopeof a trench and the like, increasing use is being made of control meansconsisting of equipment making use of lasers.

FIG. 1 illustrates schematically the utilization of an instrument ofthis kind.

In general, for the purpose of bringing ground to a desired profile useis made of rotating lasers, which serve to guide the machine (2)semi-automatically or automatically. Arrangements of this kind consistessentially of a transmitter (3) comprising the actual laser transmittermounted on a support and a receiver (4) which in turn is mounted on theactual machine. This receiver (4) comprises essentially:

receiver cells (5, 6) detecting the passage of the laser beam over 360°;

a telescopic or other mast M supporting said receiver;

a casing (7) permitting visual monitoring when the machine is operatingsemi-automatically, or a monitoring and automatic control casingpermitting visual monitoring and automatic control;

supply cables and cables connecting the cell and the casing.

For the operation of arrangements of this kind it is possible to useeither laser diode transmitters (invisible beam) or helium-neon lasertransmitters (visible beam).

In a general way, lasers of this kind are used in electronic levelinginstruments which, through the action of rotating the transmitter head(3), define a horizontal or non-horizontal reference plane P, or even avertical plane. In all cases considered in the figures the positioninformation is obtained by means of the cell (6) of the receiver (5),which may either be hand held or, preferably, mounted on a telescopic orother rod (M) fixed to the machine itself.

The present invention relates more particularly to an improvement madeto receivers mounted on the machines.

Up to the present time the receivers used for applying this techniquehave essentially consisted of a pillar carrying an assembly comprisingfour sets of photosensitive elements disposed at right angles to oneanother in order to enable a range of 360° to be covered. The fourplates are generally mounted permanently on an appropriate support andare difficult to detach, thus giving rise to a problem when one of themis broken or damaged. Receiver assemblies of this kind are thereforeexpensive to produce and in practice difficult to repair or maintain.

A new type of receiver has now been found and forms the subject of thepresent invention; this receiver makes it possible to solve theseproblems through the fact that it permits easy detachment of the platessupporting the photosensitive elements (photodiode). In addition,because of its very design, it allows the use of an assembly comprisingonly three photodiode support plates (instead of the four in receiversknown hitherto), so that its cost is substantially reduced.

Finally, the receiver according to the invention makes it possible toprevent any damage which might be caused by vibrations or shocksoccurring in the course of the use of the carrier machine.

In a general way, the invention therefore relates to an improvement madeto receivers for rotating lasers used for guiding machines (for examplepublic works machines) and which comprises (sic) a receiver cell mountedon a support enabling it to be fastened on a mast associated with themachine, this cell consisting essentially of a plurality of platescarrying photodiodes and disposed vertically in such a manner as to forma pillar enabling the passage of the beam to be detected over 360°, saidassembly being protected by a peripheral shell. The receiver accordingto the invention is characterized in that the photodiode plates arethree in number and are disposed vertically around a central shaftenabling them to be held relative to one another to form an angle of60°, said plates being detachably mounted around this shaft and theirfastening on their support casing, which enables the assembly to befixed on the machine, being achieved with the aid of damping membersdisposed at each end of the plate support shaft and around the latter.

In addition, in a preferred embodiment of the invention:

the peripheral shell is capped by a protective hood projecting beyondthe pheripheral shell and eliminating all risk of damage to said shellwhen the receiver is removed from the machine and laid on its side;

the casing supporting the receiver assembly is essentially in the formof a parallelepiped consisting of two parts articulated to one another,one part supporting the receiver proper and the other part beingprovided with means enabling said casing to be locked on a supportpillar; in an embodiment of this kind the locking is advantageouslyeffected by means of an assembly comprising a V-shaped part againstwhich the support pillar will bear, the locking of the latter beingeffected by a presser member, whose action is controlled, disposed onthe opposite face of the V.

The invention and the advantages which it provides will however bebetter understood with the aid of the example of embodiment given belowby way of indication but without constituting a limitation, andillustrated by the accompanying drawings, in which:

FIG. 1 is a schematic view of a rotating laser beam control systemincluding a receiver forming a preferred embodiment of the invention;

FIG. 2 is a schematic view in perspective of the receiver assemblyaccording to the invention;

FIG. 3 is an exploded view showing the structure of a receiver assemblyof this kind; and

FIG. 4 is a top plan view illustrating one form of construction of thecasing supporting the receiver and enabling it to be fastened on a mastassociated with the machine.

Referring to the accompanying figures, the receiver for rotating lasersaccording to the invention, which is given the general reference (5)(see FIG. 2) is essentially in the form of a receiver assembly proper(6) comprising plates (7) carrying photodiodes (8). This assembly ismounted in such a manner as to form a pillar on a support casing giventhe general reference (9), the assembly being protected by a peripheralshell (28) based on a material permeable to the laser beam and equippedwith a polarizing or electronic filter.

According to the invention, and as can be seen more particularly in FIG.3, the receiver assembly (6) comprises essentially three photodiodeplates (7) (only one of these plates being shown in FIG. 3), theseplates being disposed around a central support shaft (10) securing themand forming between them an angle of 60° to one another. According tothe invention the plates are fastened around the central shaft (10) insuch a manner that not only are they mounted detachably but the entireassembly is damped. For this purpose, as can be seen in the accompanyingFIG. 3, the central shaft (10) is surrounded by a layer of dampingmaterial (11) (for example a rubber tube), the shaft being held by twohexagonal struts (12, 13), and two top and bottom support dampingmembers (14) and (15) respectively being disposed one at each end.

The hexagonal struts (12, 13) serve not only to hold identical U-shapedsupport plates (16, 17, 18), but also to effect perfect positioning ofthe photodiode plates (7) at 60° to one another. These plates (7) areheld on the support members (16, 17, 18) by means of clamp angles (19,20) locked laterally by means of screws against the side faces of theU-shaped supports. The projecting parts of the angles (19, 20) securethe plates (7) at their sides.

An assembly of this kind is mounted on a support casing (9) ofsubstantially parallelepipedic shape, which is essentially in the formof a block comprising two parts (21, 22), one part (21) supporting theactual receiver 6 and the other part (22), which is articulated relativeto the first part, enabling said support to be locked on the holdingpillar or mast (M) associated with the machine (see FIG. 1). In thepreferred embodiment illustrated in FIGS. 2 and 3, in order to achievenot only perfect locking of the assembly around the pillar but also todamp shocks, locking is effected by providing on the part (21) of thesupport block a V-shaped zone against which the pillar (M) will bear.This V-shaped zone is covered with a layer of damping material (23), forexample rubber. The assembly is clamped around the support pillar (M) onthe one hand by means of a locking member (24) (for example a pivotinghook), and on the other hand by means of a presser system (25)consisting essentially of a shoe biased by a calibrated spring (26)which enables the pressure to be controlled. A casing of this kind thusenables the receiver to be easily installed and detached and in additionachieves perfect, precise positioning of the receiver around the supportshaft (6) mounted on the machine.

Finally, the receiver (6) is capped by a protective hood (27) (see FIG.2) projecting beyond the peripheral shell, its diameter advantageouslybeing equal to the width of the support block. In this way, when thereceiver is detached, it can be laid on its side without any risk ofdamage, because it will then be supported on the one hand on the block(9) and on the other hand on the periphery of the hood (27). Moreover,the protective hood (27) is screwed from the inside on the shaft (10),and for this purpose is provided with a blind tapped hole (not visiblein the drawings), which thus does not extend to the top face, so thatperfect leaktightness of the assembly is achieved. In addition, thisleaktightness is also improved by the provision of additional seals (notshown), which are disposed at the two ends of the shell in order toeliminate any risk of infiltration of water or dust.

In comparison with laser receivers proposed hitherto, the inventionoffers numerous advantages through the fact that it not only makes itpossible to detect the passage of the laser beam over 360° while usingonly three photodiode plates (instead of four as hitherto), but that inaddition, through its design, it permits easy detachment of thephotodiode plates for the purpose of their replacement in the event oftheir being damaged or suffering deterioration. Furthermore, since theentire assembly is mounted on damping blocks, the vibrations transmittedby the machine in normal use will not disturb the operation of theassembly. Finally, as the receiver (6) is mounted eccentrically on thesupport casing (9), relative to its mounting axis on the machine, it ispossible, by simple pivoting, to dispose it either on the outside of themachine, or in the inside if there is any risk of collision or shocks(for example when working inside a building).

The invention is obviously not restricted to the example of embodimentdescribed above, but covers all variants thereof which are based on thesame principle.

I claim:
 1. In a receiver for rotating beam lasers for guiding a machine, said receiver comprising: a receiver assembly (6) disposed on a support (9) for fastening said receiver assembly on the machine, said receiver assembly consisting essentially of plates (7) carrying photodiodes (8) disposed around a fixed shaft to form a pillar such that the laser beam can be detected over 360°, and a peripheral shell (28) capped by a protective hood (27) about said receiver assembly, the improvement wherein the photodiode (8) plates (7) are three in number, disposed vertically around a vertical, central support shaft forming an angle of 60° to one another, means for detachably mounting said plates (7) to said shaft (10) and damping members disposed at each end of the plate support shaft (10) and around the shaft (10).
 2. Receiver for rotating beam lasers according to claim 1, wherein the peripheral shell (28) is capped by a protective bond (27) which projects beyond the peripheral shell (28) and eliminates all risk of damage to said shell when the receiver is removed and laid on its side.
 3. Receiver for rotating beam lasers according to claim 1, wherein the support (9) supporting the receiver assembly (6) is essentially in the form of a parallelepiped casing consisting of two parts (21, 22) articulated to one another, one part (21) supporting the receiver assembly and the other part (22) being provided with means for locking said casing onto a support mast (M).
 4. Receiver for rotating lasers according to claim 3, wherein the locking means of the casing on the support mast (M) is effected by means of an assembly comprising a V-shaped part which bears against the mast (M), said V-shaped part being covered with a layer of damping material (23), and the clamping of the assembly around the support mast (M) being achieved by a pivoting hook locking member (24), and a presser mechanism (25) consisting essentially of a shoe biased by a calibrated spring (26) enabling the pressure to be controlled. 